Biofuels are an important addition to the energy sector. Oil and gas are under greater scrutiny from governments and consumers because of their large carbon footprint. According to the Global Carbon Project, fossil fuel emissions will hit a record high in 2022 of 4.6 billion tons. At the rate of CO2 emissions, we will exceed global warming of 1.5 degrees C in just nine years!
And…at the rate we’re emitting CO2 and other greenhouse gasses (GHG) our generation will see greater climate instability than in the history of human civilizations.
The Federal Renewable Fuel Standard was created to reduce transportation greenhouse gas emissions and expand the country’s renewable fuels sector. Many people say biofuels will save us, but not all biofuels are created equal. What do biofuels have to offer?
Environmental Impact of Fossil Fuels
Let’s set the stage by looking at the impact of fossil fuels.
Petroleum, coal, and fossil natural gas fuel your car, and they’re also used in plastic, steel, and glass production. Anything that needs to be heated or molten uses traditional fuels. That means a great many everyday objects are dependent on fossil fuels.
Our everyday choices impact climate change.
Coal, oil,.and gas are non-renewable. They’re also “dirty,” because landscape pollution is a part of resource extraction. Coal burning power plants create mercury contamination, ozone pollution, and acid rain. A crude oil spill has a devastating impact on wildlife and waters.
Fracking for natural gas extraction has ecological impacts that we’re just beginning to recognize. Natural gas is cleaner than coal and oil. Buit, is it our best alternative?
The Potential of Biofuels
“Biofuel” is an umbrella term for a number of different types of energy produced from biomass. The main fuels are biodiesel, bioethanol, renewable diesel, sustainable aviation fuel, and renewable natural gas.
Biodiesel is a widely produced biofuel, usually using a transesterification process. A percentage, from 5 to 20% of biodiesel is commonly added to petroleum diesel. Renewable diesel, produced with processes similar to those used to make petroleum diesel, can be a 100% substitute for petroleum diesel. Biodiesel, with proper modifications to a fuel system, can also be used at 100%. Large motors in trucks, ships, and construction equipment, as well as farm machinery, are fueled by diesel, renewable diesel, or a biodiesel/diesel blend. A bioethanol powered diesel engine is close to commercialization, as well.
A diesel, or compression-ignition engine, was first produced in 1895. Dr. Rudolf Diesel displayed his diesel engine at the World Exhibition in Paris in 1900 using renewable fuel. His engine used peanut oil.
We’ve come a long way since 1900. World-wide biodiesel production in 2019 has increased 234% since 2009. (EIA,2020) Soybean oil, a co-product of animal feed production, was 60% of the feedstock used to produce biodiesel. Soybeans are a good source of protein, most often used for animal feed – and world populations are growing.
Ethanol is another widely produced biofuel. As you drive around the Midwest you see large monocrop fields of corn. Little of that corn is for direct human consumption. Ethanol production uses 39% of the harvest with ⅓ of that converted to distillers dried grains with solubles (DDGS) used for animal feed, ⅓ converted to CO2 used in industry or available for carbon sequestration, and ⅓ converted to ethanol. Of the national corn harvest, 40% goes to animal feed and 15% is exported with about 5% used for sweeteners, seed, and industrial purposes.(1)
Sustainable aviation fuel (SAF) can be made from a number of processes. Currently, its production is similar to that of renewable diesel. Globally, less than 1% of current jet fuel is SAF, but policies in the US and around the world are trying to increase that use.
Renewable natural gas can be substituted 1:1 for fossil methane,
Bioenergy crops are big business. In 2021, 15 billion gallons of ethanol was produced from corn in the US. US ethanol production in 2011 was 13.6 billion gallons. An increase of 21% in just 10 years, according to the EIA. (2)
There are some major obstacles to “clean” energy from biofuels. Vehicles produced prior to 1980, according to the EPA, are not able to use biofuels. Flex-fuel vehicles (FFVs) are designed for ethanol blends ranging from – to 85% ethanol. Ethanol has less energy density than gasoline so fuel economy is lower, but the flip side is lower GHG emissions and less expensive fuel.
Feedstocks for Biofuel Production
Corn has a number of uses besides ethanol. About 5% of the US harvest is used for starch, sweeteners, and PLA fiber (a starch-based polymer called polylactic acid).
Starch and sweeteners are much more efficient uses of corn than ethanol. Even the PLA fiber used in medical sutures that naturally biodegrade is a more efficient use of corn. (3)
And, of course, corn is used in food production.
Other renewable fuel feedstocks include sugarcane, sugar beets, vegetable oil, animal fat, and other plant materials. Some of these are agricultural and forest waste products, others, such as algae, can also be used for food. Hemp waste biomass is an agricultural waste product.
Hemp – Cellulosic Biomass
Corn, soybeans, and sugarcane are all used in biofuel production. All these crops are also valuable food crops for a growing population.
Studies show that hemp biomass, with a greater lignocellulosic content, provides a higher net energy ratio. Hemp biomass also isn’t a food source. So, why aren’t we using hemp now as a biofuel? Processing takes an extra step.
Hemp stands straight and tall. That’s because of the lignin in the stalk. As the plant reaches maturity the percentage of lignin increases. More energy is needed to separate the cellulose and hemicellulose, which are easier to process, from the lignin, which is very recalcitrant. Hemp harvested while green has less lignin. Several methods, including physical, chemical, biological, and physicochemical, are used to increase the cellulosic sugar recovery to create a higher yield of ethanol.
Hemp biomass, including leaves, stem, and inflorescences has a cellulose content of 80%. But producing ethanol from hemp takes an extra step not needed with corn, soy, sugarcane, or other ethanol feedstocks.
Research is ongoing to find more economical ways to separate the cellulose from the lignin.
Industrial hemp has many uses. Fior example, a farmer growing grain hemp or food has a great deal of biomass left in his field at the end of harvest. Part of that, left as crop residue, will be food for soil biology, but some of the stalk might be used as a source of hemp biodiesel. That would give a farmer two revenue streams.
Hemp stalks, or hurd, may be destined to a processor who will be using it for composite building materials or bioplastics. But at the end of the day, even the processor will have waste products. It may be in the form of dust, hemp hurds, or stalks that didn’t feed well into the processing machine.
There are ever-expanding uses of hemp. Just as regenerative ranchers are now looking to use all parts of a steer, hemp growers want to market all the hemp material for economic benefit to their farms.
If Patagonia can use the ”waste” steer hide to make shoes and handbags, why can’t a biofuel manufacturer use processed hemp “waste” to make biofuels?
The Value of Hemp Waste for the Biofuel Industry
Biofuels might be made from the dust, stalks, seed hulls, and other waste products from hemp processing. This is where hemp shines and has the best biofuel potential.
Hemp waste is a perfect raw material for ethanol production.
The production of ethanol from hemp requires the right mix of enzymes, microorganisms,and/or properly pretreated biomass. The reduction in GHG emissions, energy supply security, and a stimulation of the agricultural economy all favor continued ethanol research. Hemp biofuels could be part of the solution to our current issue of global warming.